[123.06] Magnetic flux observed over entire solar disk

Willam Livingston (NOAO/NSO), Sami Solanki (ETH, Zurich)

A single channel Babock-type magnetograph, using the favorable
Fe 1.5648 $\mu$m (g=3) line, reveals fields everywhere from
equator to the polar limb. Good seeing is essential. Experimental
setup includes a 2.5 arcsec image slicer as the input, the NIM
modulator driven at 20Hz, and an exit slit of 0.20\AA. Noise is
5 ($10^{-3}$) percent polarization with a time constant of 3 sec
and is negligible. Presumably we mainly sense the intranetwork
fields in agreement with S. Martin (1988). New results are that the
fields (flux) may strengthen near the limb and that the best
signal is obtained at line center. The latter could indicate
unresolved doppler shifts or the transverse Zeeman effect. (Both
circular and linear polarized light is detected by the modulator).
Field strength will be deduced by a statistical analysis of
signal vs. position on the line profile.